Surface treated additive manufacturing printhead nozzles and methods for the same

ABSTRACT

Nozzles for additive manufacturing and methods for improving wettability of the nozzles are disclosed. The nozzle may include a body having an inner surface and an outer surface. The inner surface may define an inner volume of the nozzle, and may have a water contact angle of greater than 1° and less than about 90°. The method may include subjecting the nozzle to a surface treatment. The surface treatment may include plasma treating a surface of the nozzle such that free radicals, polar functional groups, or a combination thereof are formed at the surface of the nozzle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/898,607, filed on Sep. 11, 2019, which is incorporated herein byreference to the extent consistent with the present disclosure.

TECHNICAL FIELD

The presently disclosed embodiments or implementations are directed tonozzles, such as nozzles for additive manufacturing devices or 3Dprinters, and methods for improving wetting or wettability of respectivesurfaces of the nozzles.

BACKGROUND

Magnetohydrodynamic (MHD) liquid metal jetting processes eject liquid ormolten metal drops through a nozzle. To effectively facilitate theejection of the liquid metal drops through the nozzle, it is necessarythat the liquid metal sufficiently wets an inside surface of the nozzle.Conventional materials that may be used to fabricate the nozzles for MHDprintheads, however, are not naturally wettable by liquid metal.Further, the materials utilized for the nozzles must be tolerable ofrelatively high temperatures, not very conductive, non-magnetic, andmachinable. As such, ceramics or graphite are often utilized tofabricate the printhead housing and nozzles of MHD printheads. Ceramicsand graphite, however, do not exhibit sufficient liquid metal wetting.

In view of the foregoing, conventional nozzles may often include acoating, such as a metallic wetting enhancement coating disposed alongan inner surface thereof. For example, conventional nozzles may ofteninclude a nickel coating applied to the inner surface thereof via avapor deposition or plating process. While the coating enhances liquidmetal wetting along the inner surface of the nozzle, the coating alsopresents additional problems and challenges. For example, the coatingmay often interact with the liquid metal. In another example, thecoating may introduce contamination that may eventually clog the nozzle.

What is needed, then, are improved nozzles and methods for improvingwetting or wettability of the nozzles.

SUMMARY

The following presents a simplified summary in order to provide a basicunderstanding of some aspects of one or more embodiments of the presentteachings. This summary is not an extensive overview, nor is it intendedto identify key or critical elements of the present teachings, nor todelineate the scope of the disclosure. Rather, its primary purpose ismerely to present one or more concepts in simplified form as a preludeto the detailed description presented later.

The present disclosure may provide a method for improving wettability ofa nozzle for an additive manufacturing device. The method may includesubjecting the nozzle to a surface treatment. The surface treatment mayinclude plasma treating a surface of the nozzle. The plasma treatmentmay at least partially forms free radicals, polar functional groups, orcombinations thereof at the surface of the nozzle.

In some examples, the surface treatment may include plasma treating aninner surface of the nozzle.

In some examples, plasma treating the inner surface of the nozzle mayinclude orienting the nozzle at an off-axis orientation relative to aplasma of the plasma treatment.

In some examples, orienting the nozzle at the off-axis orientation mayinclude disposing the nozzle on a fixture configured to maintain thenozzle at the off-axis orientation.

In some examples, plasma treating the inner surface of the nozzlefurther may include rotating the nozzle about a vertical axis thereof.

In some examples, the fixture may protect an end surface of the nozzlefrom the plasma treatment.

In some examples, the method may further include masking an end surfaceof the nozzle before subjecting the nozzle to the surface treatment.

In some examples, the surface treatment may include plasma treating thenozzle in a plasma oven.

In some examples, the surface treatment may include plasma treating aninner surface of the nozzle and an end surface of the nozzle.

In some examples, the method may further include removing a portion ofthe nozzle disposed adjacent the end surface of the nozzle.

In some examples, removing the portion of the nozzle disposed adjacentthe end surface of the nozzle may include one or more of milling,filing, sanding, abrading, or combinations thereof.

In some examples, the surface treatment may include plasma treating thesurface of the nozzle for a period of time of from about 1 min to about60 min.

In some examples, the nozzle may be fabricated from graphite.

In some examples, the method may further include subjecting the nozzleto a post-treatment process to preserve the surface treatment of thenozzle. The post-treatment process may include contacting the surface ofthe nozzle with an intermediate sacrificial material.

In some examples, the post-treatment process may further include coolingthe nozzle with the intermediate sacrificial material contacting thesurface of the nozzle.

In some examples, the method may not include depositing a coating on thesurface of the nozzle.

The present disclosure may provide a nozzle for additive manufacturing.The nozzle may include a body having an inner surface and an outersurface. The inner surface may define an inner volume of the nozzle, andthe inner surface of the nozzle may have a water contact angle ofgreater than 1° and less than about 90°.

The present disclosure may provide a nozzle for additive manufacturing.The nozzle may include a body having an inner surface and an outersurface. The inner surface may define an inner volume of the nozzle. Theinner surface of the nozzle may be subjected to a surface treatment suchthat the inner surface includes increased free radicals and/or polarfunctional groups as compared to an untreated surface of the nozzle.

In some examples, a coating is not disposed on the inner surface and theouter surface of the nozzle.

In some examples, the nozzle may further include an intermediatesacrificial material disposed in the inner volume of the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentteachings. These and/or other aspects and advantages in the embodimentsof the disclosure will become apparent and more readily appreciated fromthe following description of the various embodiments, taken inconjunction with the accompanying drawings of which:

FIG. 1A illustrates a schematic cross-sectional view of an exemplary 3Dprinter, according to one or more embodiments disclosed.

FIG. 1B illustrates an enlarged view of the nozzle of the 3D printerindicated by the box labeled “1B” of FIG. 1A, according to one or moreembodiments disclosed.

FIG. 2 is a plot illustrating the growth of occlusions in the controlnozzle of Example 1.

FIG. 3 is a plot illustrating the growth of occlusions in the testnozzle of Example 1.

DETAILED DESCRIPTION

The following description of various typical aspect(s) is merelyexemplary in nature and is in no way intended to limit the disclosure,its application, or uses.

As used throughout, ranges are used as shorthand for describing each andevery value that is within the range. Any value within the range may beselected as the terminus of the range. In addition, all references citedherein are hereby incorporated by reference in their entireties. In theevent of a conflict in a definition in the present disclosure and thatof a cited reference, the present disclosure controls.

Additionally, all numerical values are “about” or “approximately” theindicated value, and take into account experimental error and variationsthat would be expected by a person having ordinary skill in the art. Itshould be appreciated that all numerical values and ranges disclosedherein are approximate values and ranges, whether “about” is used inconjunction therewith. It should also be appreciated that the term“about,” as used herein, in conjunction with a numeral refers to a valuethat may be ±0.01% (inclusive), ±0.1% (inclusive), ±0.5% (inclusive),±1% (inclusive) of that numeral, ±2% (inclusive) of that numeral, ±3%(inclusive) of that numeral, ±5% (inclusive) of that numeral, ±10%(inclusive) of that numeral, or ±15% (inclusive) of that numeral. Itshould further be appreciated that when a numerical range is disclosedherein, any numerical value falling within the range is alsospecifically disclosed.

As used herein, the term “or” is an inclusive operator, and isequivalent to the term “and/or,” unless the context clearly dictatesotherwise. The term “based on” is not exclusive and allows for beingbased on additional factors not described, unless the context clearlydictates otherwise. In the specification, the recitation of “at leastone of A, B, and C,” includes embodiments containing A, B, or C,multiple examples of A, B, or C, or combinations of A/B, A/C, B/C,A/B/B/ BB/C, AB/C, etc. In addition, throughout the specification, themeaning of “a,” “an,” and “the” include plural references. The meaningof “in” includes “in” and “on.”

Reference will now be made in detail to exemplary embodiments of thepresent teachings, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same, similar, or like parts.

The present disclosure is directed to nozzles, such as nozzles foradditive manufacturing devices or 3D printers, and methods for improvingwetting or wettability of respective surfaces (e.g., inner and/or outersurfaces) of the nozzles. As used herein, the term “wettability” or thelike may refer to the ability of a liquid to maintain contact with asolid surface, resulting from intermolecular interactions when theliquid and the solid are brought together or contacted with one another.A degree of wetting or wettability may be determined by a force balancebetween adhesive and cohesive forces. Adhesive forces between the liquidand the solid may cause a liquid drop to spread across the surface.Cohesive forces within the liquid may cause the drop to “ball up” andavoid contact with the surface. A relatively higher wettability of asurface towards a specific liquid implies that the specific liquid willspread to a higher degree across the solid surface. As further describedherein, the methods may include exposing or subjecting respectivesurfaces of the nozzles to one or more surface treatments to therebymodify (e.g., chemically modify) the respective surfaces of the nozzles.The surface treatments may directly modify the respective surfaces ofthe nozzles, and thereby improve wettability of the respective surfaceswithout a coating.

FIG. 1A illustrates a schematic cross-sectional view of an exemplaryadditive manufacturing layering device or 3D printer 100 that mayutilize the nozzles disclosed herein, according to one or moreembodiments. The 3D printer 100 may be a magnetohydrodynamic (MHD)printer. It should be appreciated, however, that any additivemanufacturing device may utilize the nozzles and methods disclosedherein. The 3D printer 100 may include a body 102, which may also bereferred to herein as a pump chamber, one or more heating elements (oneis shown 104), one or more metallic coils 106, a stage 108, a substrate110, a computing system 112, or any combination thereof, operablycoupled with one another. As illustrated in FIG. 1A, the heatingelements 104 may be at least partially disposed about the body 102, andthe metallic coils 106 may be at least partially disposed about the body102 and/or the heating elements 104. As further illustrated in FIG. 1A,the substrate 110 may be disposed on the stage 108 and below the body102. The body 102 may include an inner surface 114 defining an innervolume 116 thereof. The body 102 may define a nozzle 118 disposed at afirst end portion 120 thereof. FIG. 1B illustrates an enlarged view ofthe nozzle 118 of the 3D printer 100, indicated by the box labeled “1B”of FIG. 1A, according to one or more embodiments.

In an exemplary operation of the 3D printer 100 with continued referenceto FIGS. 1A and 1B, a build material (e.g., metal) from a source 122 maybe directed to the inner volume 116 of the body 102. The heatingelements 104 may at least partially melt the build material contained inthe inner volume 116 of the body 102. For example, the build materialmay be a solid, such as a solid metal, and the heating elements 104 mayheat the body 102 and thereby heat the build material from a solid to aliquid (e.g., molten metal). The metallic coils 106 may be coupled witha power source (not shown) capable of or configured to facilitate thedeposition of the build material on the substrate 110. For example, themetallic coils 106 and the power source coupled therewith may be capableof or configured to generate a magnetic field, which may generate anelectromotive force within the body 102, thereby generating an inducedelectrical current in the molten metal disposed in the body 102. Themagnetic field and the induced electrical current in the molten metalmay create a radially inward force on the liquid metal, known as aLorenz force, which creates a pressure at the nozzle 118. The pressureat the nozzle 118 may expel the molten metal out of the nozzle 118toward the substrate 110 and/or the stage 108 in the form of one or moredrops.

Referring back to FIG. 1B, the nozzle 118 may include or be fabricatedfrom one or more ceramic and/or graphitic materials. Illustrativeceramic and/or graphitic materials may be or include, but are notlimited to, graphite, boron nitride, silicon nitride, aluminum nitride,aluminum oxide, composites thereof, or combinations thereof.

In at least one embodiment, a portion 126 of the inner surface 114, aportion 128 of an outer surface 124, and/or a portion 132 of an endsurface 134 of the body 102 or the nozzle 118 thereof may be modified.For example, as further described herein, the inner, outer, and/or endsurfaces 114, 124, 134 of the body 102 or the nozzle 118 thereof may beexposed or subjected to one or more surface treatments or surfacetreatment processes to thereby modify respective portions 126, 128, 132of the body 102 or the nozzle 118 thereof. As used herein, theexpressions “surface treatment” or “surface treatment process” may referto a process that will modify (e.g., chemically modify) a surface toimprove the direct wetting interaction or wettability between themodified surface and a build material (e.g., molten metal). Accordingly,in at least one embodiment, the respective portions 126, 128, 132 of theinner, outer, and/or end surfaces 114, 124, 134 may be chemicallydifferent than remaining portions 130 of the nozzle 118 not exposed tothe one or more surface treatments.

In at least one embodiment, the one or more surface treatments mayinclude plasma treating the inner, outer, and/or end surfaces 114, 124,134 of the nozzle 118 with a device capable of or configured to generatea plasma. As used herein, the term or expression “plasma treatment” orthe like may refer to a process in which a gas is ionized to form plasmaand alter a surface of a material. Plasma treatment may includeintroducing one or more gases (e.g., mixture of gases) and energizingthe gases with a source of power (e.g., radio frequency). Illustrativegases that may be utilized in the plasma treatment may be or include,but are not limited to, oxygen, nitrogen, argon, hydrogen, carbontetrafluoride, or combinations thereof. In at least one embodiment, theplasma treatment may be conducted in a sealed chamber, such as a sealedvacuum chamber. The chamber may be maintained at a negative pressure(e.g., low pressure vacuum). In another embodiment, the plasma treatmentmay be conducted in open air/atmosphere outside of a chamber. In atleast one embodiment, the one or more gases may not need to beintroduced. For example, the device capable of or configured to generatethe plasma may not need a source of the one or more gases and/or may beconducted in atmospheric conditions. Illustrative devices may be orinclude PLASMA WAND, which is commercially available from Plasma Etch,Inc. of Carson City, NV.

In at least one embodiment, the device capable of or configured togenerate the plasma may be a plasma oven maintained at a low pressure.It should be appreciated that in some plasma ovens, the plasma uses ionsthat may be directionally accelerated in a radio frequency (RF) field.For example, in some plasma ovens, the plasma uses ions that areaccelerated downward in the RF field, thereby providing the plasma inthe downward direction. In such plasma ovens, it may be difficult tosubject some surfaces, such as the inner surface 114 of the nozzle 118to the plasma. As such, in at least one embodiment, the plasma treatmentmay include orienting or maintaining the nozzle 118 at a slightlyoff-axis orientation to facilitate contact between the directionalplasma and the target surfaces 114, 124, 134 of the nozzle 118. Forexample, FIG. 2 illustrates the nozzle 118 maintained at an off-axisorientation to facilitate contact between the directional plasma 200 andthe inner surface 114 of the nozzle 118. In an exemplary embodiment,illustrated in FIG. 2, a fixture or support 202 may be utilized tomaintain the off-axis orientation of the nozzle 118. As illustrated inFIG. 2, the fixture 202 may orient the nozzle 118 such that a verticalaxis 204 of the nozzle 118 may be angled or may form an angle (θ) withrespect to a vertical axis 206 of the fixture 202. The angle (θ) may beany angle to allow contact between the directional plasma 200 and theinner surface 114 of the nozzle 118. In at least one embodiment, thenozzle 118 may be rotated to facilitate complete radial contact betweenthe directional plasma 200 and the radial inner surface 114 of thenozzle 118. For example, the nozzle 118 may be rotated about thevertical axis 204 to thereby facilitate contact between the directionalplasma 200 and the radial inner surface 114 thereof. It should beappreciated that the fixture 202 may also protect or prevent the endsurface 134 of the nozzle 118 from being subjected to the surfacetreatment, thereby maintaining the end surface 134 in a native,untreated state.

In at least one embodiment, all of the inner, outer, and/or end surfaces114, 124, 134 of the nozzle 118 may be subjected to the one or moresurface treatments. In another embodiment, only one of the inner, outer,and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected tothe one or more surface treatments. For example, only the inner surface114 of the nozzle 118 is subjected to the one or more surfacetreatments. In another example, only the outer surface 124 of the nozzle118 is subjected to the one or more surface treatments. In yet anotherexample, only the end surface 134 of the nozzle 118 is subjected to theone or more surface treatments.

In a preferred implementation, the end surface 134 of the nozzle 118 isnot subjected to the one or more surface treatments or the end surface134 is subjected to the one or more surface treatments, but portions 132of the nozzle 118 that are modified are subsequently removed from thenozzle 118. For example, in at least one embodiment, the surfacetreatment may include subjecting the end surface 134 to the plasmatreatment to modify the portion 134 or the end surface 134, andsubsequently removing the modified portion 134 or end surface 134 via asubsequent process. The subsequent process to remove the modifiedportion 134 and/or the end surface 134 may include any physical processsufficient to remove material (e.g., graphite) from the nozzle 118. Forexample, the subsequent process to remove the modified portion 134and/or the end surface 134 may include milling, filing, sanding,abrading, or the like, or combinations thereof. In at least oneembodiment, the surface treatment may include masking, protecting, orotherwise covering the end surface 134 of the nozzle 118 prior to theplasma treatment to thereby prevent modification of the end surface 134and the portion 132.

The inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118may be subjected to the one or more surface treatments for an amount oftime sufficient to substantially or completely modify the respectivesurfaces 114, 124, 134 or the respective portions 126, 128, 132 of thenozzle 118. In at least one embodiment, the inner, outer, and/or endsurfaces 114, 124, 134 of the nozzle 118 may be subjected to the one ormore surface treatments for a period of from about 1 min to about 60min. For example, the inner, outer, and/or end surfaces 114, 124, 134 ofthe nozzle 118 may be subjected to the one or more surface treatmentsfor a period of from about 1 min, about 5 min, about 10 min, about 15min, about 20 min, about 30 min, about 40 min, about 50 min, or about 55min to about 60 min. In another example, the inner, outer, and/or endsurfaces 114, 124, 134 of the nozzle 118 may be subjected to the one ormore surface treatments for a period of from about 1 min to about 5 min,about 10 min, about 15 min, about 20 min, about 30 min, about 40 min,about 50 min, about 55 min, or about 60 min. In yet another example, theinner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may besubjected to the one or more surface treatments for a period of fromabout 1 min, about 5 min, about 10 min, about 15 min, about 20 min, orabout 30 min to about 40 min, about 50 min, about 55 min, or about 60min.

In an exemplary embodiment, the nozzle 118 may be fabricated fromgraphite. Without being bound by theory, it is believed that the surfacetreatment with the plasma may at least partially clean the respectivesurfaces 114, 124, 134 of the nozzle 118. It is also believed that theplasma may at least partially form or produce free radicals, therebymaking the respective surfaces 114, 124, 134 relatively more reactive.It is further believed that the plasma may at least partially form polarfunctional groups at the respective surfaces 114, 124, 134. Illustrativepolar functional groups are known in the art and may at least partiallydepend on the material used to fabricate the nozzle 118, one or moreparameters of the plasma treatment, or combinations thereof. As furtherdiscussed herein, the wettability may be measured with a goniometer. Assuch, the degree of the plasma treatment may be measured with thegoniometer as well.

The respective portions 126, 128, 132 of the nozzle 118 that aremodified with the surface treatment may have a thickness of from about 1Angstrom (Å) to about 500 Å. For example, the respective portions 126,128, 132 of the nozzle 118 that are modified with the surface treatmentmay have a thickness of from about 1 Å, about 5 Å, about 10 Å, about 50Å, about 100 Å, or about 150 Å to about 200 Å, about 250 Å, about 300 Å,about 350 Å, about 400 Å, or about 500 Å. In another example, therespective portions 126, 128, 132 of the nozzle 118 that are modifiedwith the surface treatment may have a thickness of greater than 1 Å andless than or equal to 500 Å, less than or equal to 400 Å, less than orequal to 300 Å, less than or equal to 200 Å, less than or equal to 100Å, less than or equal to 50 Å, or less than or equal to 10 Å. In yetanother example, the respective portions 126, 128, 132 of the nozzle 118that are modified with the surface treatment may have a thickness offrom about 1 Å to about 500 Å, about 100 Å to about 400 Å, or about 200Å to about 300 Å. It should be appreciated that the thickness of therespective portions 126, 128 are significantly thinner than a coating,such as a coating prepared from electroless plating (e.g., nickelcoating), which may have a thickness of from about 1 μm to about 100 μm,more typically from about 10 μm to about 25 μm.

As used herein, the expression “water contact angle” may refer to theangle that deionized water or a test liquid contacts a surface. Thewater contact angle may be measured with any suitable goniometer. Theinner, outer, and/or end surfaces 114, 124, 134 of the nozzles 118 thatare modified via the surface treatment may have a water contact angle ofgreater than 1° and less than about 90°, less than about 50°, less thanabout 40°, less than about 30°, less than about 25°, less than about20°, less than about 15°, or less than about 10°. In another example,the inner, outer, and/or end surfaces 114, 124, 134 of the nozzles 118that are modified via the surface treatment may have a water contactangle of from about 1° to about 90°, about 5° to about 80°, about 10° toabout 70°, about 15° to about 60°, about 20° to about 50°, or about 20°to about 40°. Illustrative test liquids may be or include, but are notlimited to, water, ethylene glycol, diiodomethane, or the like, orcombinations thereof.

In at least one embodiment, the inner, outer, and/or end surfaces 114,124, 134 of the nozzles 118 that are modified via the surface treatmentmay have a relatively smoother surface (e.g., less roughness) ascompared to an untreated surface.

In at least one embodiment, the surface treated inner, outer, and/or endsurfaces 114, 124, 134 and/or the modified portions 126, 128, 132 of thenozzle 118 may be exposed or subjected to a subsequent or post-treatmentprocess capable of or configured to at least partially protect ormaintain the surface treated properties of the modified inner, outer,and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128,132 of the nozzle 118. For example, the surface treated inner, outer,and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128,132 may exhibit gradual losses of the functionality when exposed toatmospheric conditions. As such, the inner, outer, and/or end surfaces114, 124, 134 and/or the modified portions 126, 128, 132 may besubjected to a subsequent process that may at least partially halt,reduce, or otherwise slow the loss of functionality, thereby at leastpartially preserving the functionality.

In at least one embodiment, the post-treatment process may includestoring and/or sealing the treated nozzles 118 in vacuum-packed,hermetically sealed bags. In another embodiment, the post-treatmentprocess may include contacting the inner, outer, and/or end surfaces114, 124, 134 and/or the modified portions 126, 128, 132 with anintermediate sacrificial material. The inner, outer, and/or end surfaces114, 124, 134 and/or the modified portions 126, 128, 132 of the nozzle118 may be contacted with the intermediate sacrificial materialimmediately after the surface treatment, or shortly thereafter. Forexample, the respective surfaces 114, 124 and/or the modified portions126, 128 may be contacted with the intermediate sacrificial materialwithin about 2 hours of the surface treatment (e.g., about 0 hours toabout 2 hours). In at least one embodiment, the post-treatment processmay also include draining the intermediate sacrificial material from thenozzle 118. The post-treatment process may also include subsequentlycooling the nozzle 118 for storage. In some examples, the intermediatesacrificial material may not be drained from the nozzle 118 prior tocooling. As such, the nozzle 118 may be cooled with the intermediatesacrificial material disposed in the inner volume 116 and/or with theintermediate sacrificial material contacting the inner, outer, and/orend surfaces 114, 124, 134.

The intermediate sacrificial material may have thermal expansionproperties similar or substantially similar to the nozzle 118 to therebymaintain structural integrity (e.g., reduce cracking) of the nozzle 118while cooling the nozzle 118. For example, the intermediate sacrificialmaterial may have similar thermal expansion properties to the nozzle 118at a temperature of from about room temperature to a melting point ofthe intermediate sacrificial material.

The intermediate sacrificial material may have a relatively low meltingpoint to thereby introduce less thermal stress, and enable displacementby a molten build material or a primary jetting metal during printing.The melting point of the intermediate sacrificial material may besubstantially equal to or less than an operating temperature or meltingtemperature of the build material. For example, the melting point of theintermediate sacrificial material may be from about 400° C., about 450°C., about 500° C., or about 560° C. to about 660° C., about 700° C.,about 750° C., about 800° C., about 900° C., about 1000° C., about 1100°C., about 1200° C., about 1400° C., or about 1500° C.

The intermediate sacrificial material may be compatible with the buildmaterial or the primary jetting metal. For example, the intermediatesacrificial material may at least partially dissolve or combine with themolten build material during jetting, thereby replacing or removing theintermediate sacrificial material from the nozzle 118 during printing orjetting. It should be appreciated that the intermediate sacrificialmaterial introduced into the nozzle 118 does not form a coating duringnormal printing operations or processes. For example, during a printingprocess the molten build material flowing through the nozzle 118 willdisplace, eject, or otherwise remove the intermediate sacrificialmaterial from the nozzle 118.

The intermediate sacrificial material may be or include one or moremetals, metal alloys, or combinations thereof. Illustrative metals andmetal alloys that may be utilized for the intermediate sacrificialmaterial may be or include, but are not limited to, the build materialintended to be utilized in the 3D printer 100, aluminum, one or moresoldering alloys, metals having a melting point of from about 500° C. toabout 700° C., about 560° C. to about 660° C., or lower, or the like, orany combination thereof.

As used herein, the term or expression “coating” may refer to a physicalbarrier that separates an original or native surface of the nozzle 118from a build material (e.g., molten metal) flowing through and/orcontained in the nozzle 118. For example, a coating may refer to amaterial deposited (e.g., post-fabrication of the nozzle 118) on theinner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 toseparate the inner, outer, and/or end surfaces 114, 124, 134 of thenozzle 118 from the molten metal flowing through and/or contained in theinner volume 116 of the nozzle 118. A coating may result in theformation of two interfaces or surface interfaces. For example, acoating may create an interface between inner, outer, and/or endsurfaces 114, 124, 134 of the nozzle 118 and the coating. In anotherexample, the coating may create an interface between the coating and themolten metal flowing through and/or contained in the nozzle 118. Asnoted above, coatings may generally have a thickness of from about 1 μmto about 100 μm, or more typically from about 10 μm to about 25 μm.Coatings may be deposited via various processes/techniques, such assputtering, evaporation, electroplating, electroless plating, or thelike, or any combination thereof. In at least one embodiment, the nozzle118 disclosed herein may not include a coating. For example, the nozzle118 and the inner, outer, and/or end surfaces 114, 124, 134 thereof maybe free or substantially free of a coating. Accordingly, the inner,outer, and/or end surfaces 114, 124, 134 and/or the respective modifiedportions 126, 128, 132 of the nozzle 118 may directly contact the meltedbuild material (e.g., molten metal) flowing through or contained in thenozzle 118

EXAMPLES

The examples and other implementations described herein are exemplaryand not intended to be limiting in describing the full scope ofcompositions and methods of this disclosure. Equivalent changes,modifications and variations of specific implementations, materials,compositions and methods may be made within the scope of the presentdisclosure, with substantially similar results.

Example 1

A plurality of nozzles were subjected to surface treatment and evaluatedfor jetting stability and contamination or occlusion growth.Particularly, graphite nozzles were treated with a plasma. It wasobserved that plasma treating for about 15 sec to about 20 sec improvedwettability of the nozzles. The treated nozzles produced straightstreams of the molten metal when utilized in a liquid metal jettingprocess. It was also observed that the meniscus formed in treatednozzles were flush with the respective end surfaces thereof. It wasfurther observed that plasma treating the nozzles prevented occlusiongrowth in the nozzles.

The present disclosure has been described with reference to exemplaryimplementations. Although a limited number of implementations have beenshown and described, it will be appreciated by those skilled in the artthat changes may be made in these implementations without departing fromthe principles and spirit of the preceding detailed description. It isintended that the present disclosure be construed as including all suchmodifications and alterations insofar as they come within the scope ofthe appended claims or the equivalents thereof.

What is claimed is:
 1. A method for improving wettability of a nozzlefor an additive manufacturing device, the method comprising subjectingthe nozzle to a surface treatment, wherein the surface treatmentcomprises plasma treating a surface of the nozzle, wherein the plasmatreatment at least partially forms free radicals, polar functionalgroups, or combinations thereof at the surface of the nozzle.
 2. Themethod of claim 1, wherein the surface treatment comprises plasmatreating an inner surface of the nozzle.
 3. The method of claim 2,wherein plasma treating the inner surface of the nozzle comprisesorienting the nozzle at an off-axis orientation relative to a plasma ofthe plasma treatment.
 4. The method of claim 3, wherein orienting thenozzle at the off-axis orientation comprises disposing the nozzle on afixture configured to maintain the nozzle at the off-axis orientation.5. The method of claim 4, wherein plasma treating the inner surface ofthe nozzle further comprises rotating the nozzle about a vertical axisthereof.
 6. The method of claim 4, wherein the fixture protects an endsurface of the nozzle from the plasma treatment.
 7. The method of claim1, further comprising masking an end surface of the nozzle beforesubjecting the nozzle to the surface treatment.
 8. The method of claim1, wherein the surface treatment comprises plasma treating the nozzle ina plasma oven.
 9. The method of claim 1, wherein the surface treatmentcomprises plasma treating an inner surface of the nozzle and an endsurface of the nozzle.
 10. The method of claim 9, further comprisingremoving a portion of the nozzle disposed adjacent the end surface ofthe nozzle.
 11. The method of claim 10, wherein removing the portion ofthe nozzle disposed adjacent the end surface of the nozzle comprises oneor more of milling, filing, sanding, abrading, or combinations thereof.12. The method of claim 1, wherein the surface treatment comprisesplasma treating the surface of the nozzle for a period of time of fromabout 1 min to about 60 min.
 13. The method of claim 1, wherein thenozzle is fabricated from graphite.
 14. The method of claim 1, furthercomprising subjecting the nozzle to a post-treatment process to preservethe surface treatment of the nozzle, wherein the post-treatment processcomprises contacting the surface of the nozzle with an intermediatesacrificial material.
 15. The method of claim 14, wherein thepost-treatment process further comprises cooling the nozzle with theintermediate sacrificial material contacting the surface of the nozzle.16. The method of claim 1, wherein the method does not comprisedepositing a coating on the surface of the nozzle.
 17. A nozzle foradditive manufacturing, comprising a body having an inner surface and anouter surface, wherein the inner surface defines an inner volume of thenozzle, and wherein the inner surface of the nozzle comprises a watercontact angle of greater than 1° and less than about 90°.
 18. A nozzlefor additive manufacturing, comprising a body having an inner surfaceand an outer surface, wherein the inner surface defines an inner volumeof the nozzle, and wherein the inner surface of the nozzle is subjectedto a surface treatment such that the inner surface comprises increasedfree radicals and/or polar functional groups as compared to an untreatedsurface of the nozzle.
 19. The nozzle of claim 18, wherein a coating isnot disposed on the inner surface and the outer surface of the nozzle.20. The nozzle of claim 18, further comprising an intermediatesacrificial material disposed in the inner volume of the nozzle.